All the standard Mach3 screens, and as far as I know, all the wizards (except for the latest one Ron did) are set out in such a way as to leave the bottom of the screen empty; leaving space for the standard windows task bar.

I think this is a good principal to follow especially if doing screens for others to use.

Again IMO there are valid reasons to shy away from auto screen enlarge. I don't expect others to share that opinion.

Thanks guys, upon further reflection, I've realized my question may have been simplistic - programs can alter the size of the bars pragmatically and I believe users can also by fiddling with display themes etc.... I think I'll simply assume mach uses the default size bars and go from there (not sure how much that is yet, but I'll figure out some way to measure it).

On a 1024x768 screen, with mach at full screen, once you deduct the title and menu bars and the borders, I believe the area left for screen pages is 1016 x 719 pixels. ...that also happens to be the size the mach blue screens use for background images also (so I guess those guy already figured out this bit of trivia).

Curiously the mach standard 1024 screen set is 967x725 - I find that test screens at 725 high cut off the bottom few pixels when displayed in mach.

So, I'm going with 1016x719 as the magic size and will let "auto enlarge" handle physical screens other than 1024x768.